Question

--- Listen! David is talking happily with his mother in the next room.
　--- It ______ be his mother. She has gone to Yunnan to be a volunteer doctor.

A．should

B．must

C．can’t

D．mustn’t

Answer 1

C

考查情景交際和情態動詞。“聽！大衛在隔壁正在高興地和媽媽談話。”“她不可能是他的媽媽，她媽媽作為一名志愿醫生，已經去云南了。”情態動詞可表推測。Should“應該”；must“一定”；can’t“不可能”；musn’t“”禁止不，表推測。故選C。